Wikipedia is a multilingual, free-content encyclopedia project. There are more than 200 different language editions, with more than 4 million articles, forming the largest publicly available and editable knowledgebase.
Wiktionary is a project to create free-content dictionaries and thesauri in every language.
Wikibooks aims to build a collection of free e-book resources, including textbooks, language courses, manuals, and annotated public domain books. It aims to help both (self-)instruction of students, and teachers in high schools and universities.
Wikiquote is a repository of quotations taken from famous people, books, speeches, films or any intellectually interesting materials. Proverbs, mnemonics or slogans are also included in Wikiquote.
Wikimedia Commons 
Wikimedia Commons was launched to provide a central repository for video, images, music, and spoken text. Commons now has hundreds-of-thousands of multimedia files. All files on Commons use free licenses, allowing them to be used for any purpose, even by non-Wikimedia projects.
Wikisource is a collection of free-content source documents, such as books, journals, laws, and letters. These documents are digitized, annotated and translated collaboratively by volunteers, and cross-referenced in other relevant Wikimedia projects like Wikipedia.
Wikinews’ mission is to report news on a wide variety of subjects, providing a free-content alternative to commercial news; contributors from around the world collaborate on news articles. The articles in the currently over 10 language editions are either original reports or summaries of news from external sources. All articles are required to be written from a neutral point of view.